In 2009, we laid the groundwork for our studies, starting with obtaining approval from our institutional review board for a new research protocol that allows us to collect skin biopsies from transplanted FHLH patients. This protocol permits us not only to isolate germline DNA (from other than the transplanted blood cells), but also to establish fibroblast cultures needed for generating inducible pluripotent stem cells (iPS) cells. We have started growing fibroblast cultures from normal healthy volunteers as a prelude to doing the same in our patients. Because our candidate gene studies, focusing on the previously mapped 9p21 locus, have so far been unrevealing in several FHLH patient samples, we are planning a new gene linkage study to confirm and extend this finding. For this study, we have collected approximately half of the DNA samples from the parents and affected offspring of multiplex families that have no known mutations. Our study will be powered to detect two loci.